21688752 has 40 divisors (see below), whose sum is σ = 57965040. Its totient is φ = 6979840.

The previous prime is 21688741. The next prime is 21688759. The reversal of 21688752 is 25788612.

It is a self number, because there is not a number n which added to its sum of digits gives 21688752.

It is not an unprimeable number, because it can be changed into a prime (21688759) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6399 + ... + 9182.

It is an arithmetic number, because the mean of its divisors is an integer number (1449126).

Almost surely, 2^21688752 is an apocalyptic number.

It is an amenable number.

21688752 is an abundant number, since it is smaller than the sum of its proper divisors (36276288).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21688752 is a wasteful number, since it uses less digits than its factorization.

21688752 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15621 (or 15615 counting only the distinct ones).

The product of its digits is 53760, while the sum is 39.

The square root of 21688752 is about 4657.1184223724. The cubic root of 21688752 is about 278.8762442365.

The spelling of 21688752 in words is "twenty-one million, six hundred eighty-eight thousand, seven hundred fifty-two".